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STARDUST Project CRITICAL EVENTS READINESS REVIEW COMET P/WILD 2 ENCOUNTER

STARDUST Project CRITICAL EVENTS READINESS REVIEW COMET P/WILD 2 ENCOUNTER Spacecraft/Testing/FP Status Allan Cheuvront. Overview. Spacecraft Status Encounter Requirements Encounter Commanding First Time Events Fault Protection Encounter Test Program Contingencies Staffing

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STARDUST Project CRITICAL EVENTS READINESS REVIEW COMET P/WILD 2 ENCOUNTER

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  1. STARDUST Project CRITICAL EVENTS READINESS REVIEW COMET P/WILD 2 ENCOUNTER Spacecraft/Testing/FP Status Allan Cheuvront CERR-ARC

  2. Overview • Spacecraft Status • Encounter Requirements • Encounter Commanding • First Time Events • Fault Protection • Encounter Test Program • Contingencies • Staffing • Readiness Assessment CERR-ARC

  3. Spacecraft Status • Configuration • AACS • All Stellar Mode • Transition to Gyro Based Mode for OPNAV • Power • Solar Arrays Strings Are Parallel • Battery Voltage Ranges 30-32 • Telecom • All Components Powered On Until After Encounter • Power Cycle Once/Week to Prevent Trapped Charge • FSW is Operating at 20 MHz • Thermal is Nominal • Instruments • CIDA is Operating • DFM is Powered Off • SRC is Stowed • NAVCAM is On for OPNAV CERR-ARC

  4. Spacecraft Status (Cont’d) • Performance Margins • Fuel = 9 Kg (81 m/s) • Tank Pressure = 18 psi (100 psi Minimum Required) • IMU = 60 Days (Worst Case) • Power = 100 Watts • No Concerns for Telecom, Thermal, and FSW • Spacecraft Trends • All Subsystem’s Performances are Nominal • Power Output is Slowly Decreasing Since Spacecraft is Moving Away From Sun • Thermally the Spacecraft is Also Slowly Cooling • PACI Temp Keep Out Zone Not an Issue • SSPA Is On CERR-ARC

  5. Encounter Requirements CERR-ARC

  6. Encounter Requirements (Cont’d) CERR-ARC

  7. Encounter Approach Activities CERR-ARC

  8. Close Encounter Activities -Switch to MGA -Carrier Only (E-6.5m) -DFM On, Send Data -ACS Mode-Encounter Absolute -Reallocate Heap -NAVCAM to Encounter Mode -CIDA to Encounter Mode -Start sending CIDA data -Start APID 28 -Nav Mirror to Auto Track -Take 1 Image And Downlink -Stop DFM & CIDA Data (E-7m) -Roll Mnvr (E-6m) -Take 1 Image E-6h E-5h E-4h E-3h E-2h E-1h E-30m E-15m E-0 -Images Every 10 Seconds (E-6m) - Sequence Start -Disable SCAM Track Mode -Start APID 27 -Config File Initialization (E-5.5h) -Disable SCAM Processing (E-2.5h) -Images Every 30 Seconds -Start APID 30 (E-13.5m) CERR-ARC

  9. Close Encounter Activities (Cont’d) -Switch to HGA (E+7m) -Stop APID 28 -CIDA to Cruise Mode -CIDA Off -Sequence End (E+5.5h) -Begin Playback -DFM Off -Enable SCAM Processing (E+2.5h) -Stop APID 30 (E+13m) E+0 E+15m E+30m E+1h E+2h E+3h E+4h E+5h E+6h -Roll Back (E+6m) -ACS Mode- AutoRef Earth Point -Stop APID 27 -Take Last Image (E+8m) -NAVCAM Off CERR-ARC

  10. Encounter Commanding • Command Encounter Mission Phase After TCM 12 • Encounter Sequence • Testing Flight Versions of All Products • All Configuration Files Have Been Reviewed • Late Updated Files Have Been Identified and Update Process Tested • Critical Commanding • TCM 12 – E-48 Hours • Finalizes Flyby Distance • 3 Hours of Margin in Schedule For Uplink • Encounter Sequence • Loaded Spacecraft at E-40 Hours • Not Time Critical • NAVCAM Image Priority FSW Patch • Plays Back 5 Closest Approach Images First • Patch Products Incorporated in All Encounter Testing • Will Be Installed on S/C by December 15 CERR-ARC

  11. Encounter Commanding (Cont’d) • Significant Commanding • Mission Phase to Encounter (Post TCM 12) • Open Latch Valve 2 (Post TCM 12) • Disable FP (Post TCM 13 or E-17 Hours) • Command Cruise 2 Mission Phase When All Science Data Has Been Played-Back And Greater Than E+4 Days CERR-ARC

  12. Encounter Uplink Schedule CERR-ARC

  13. First Time Events • First Time Events Performed at Annefrank • Disable S/W Fault Protection Entries Except • Attitude Control Fault Remained Enabled • Battery State of Charge Fault Remained Enabled • Critical Event Fault Protection Will Be Enabled • Attitude Commanded to Encounter Absolute Mode and Encounter Relative Mode • Reallocation of HEAP Space To Encounter Configuration • Command AACS To Encounter Mode • Command CIDA To Encounter Mode • Command NAVCAM to Encounter Mode • Nucleus Tracking • Reallocation of HEAP Space To Cruise Configuration (Post Annefrank) CERR-ARC

  14. First Time Events (Cont’d) • Remaining First Time Events • Autonomous Roll Maneuver • Tested and Verified in STL • Cannot Be Performed on Spacecraft • Execute the “Bang” Part of the “Bang-Bang” Controller • Demo on S/C Scheduled for Early December • Tested and Verified in STL CERR-ARC

  15. Fault Protection Analysis • Wild 2 Encounter Fault Tree Analysis Performed Prior to Annefrank and Revisited in October 2003 • 237 Potential Faults Identified • 11 Major Fault Areas • Fail to Collect 1000 Particles (61 Faults) • Encounter Velocity > 6.5 km/s (2 Faults) • Spacecraft Survivability (128 Faults) • Do Not Take > 65 Images (15 Faults) • Images Resolution > 67 mrad/pixel (1 Fault) • Images Taken > 2000 km (3 Duplicates) • CIDA Fails (5 Faults) • Failure to Collect Comet Coma Molecules (2 Duplicates) • Failure to Perform Dynamic Science (8 Faults) • DFM Fails (4 Faults) • Sequence/Command Errors (13 Faults) • Utilized STARDUST and Non-STARDUST Personnel CERR-ARC

  16. Fault Protection Analysis (Cont’d) • No Show Stoppers Were Identified • Original Review Exposed Subsystem Personnel Not Present During Design to Their Subsystem Performance Expectations • Modeling Prop Slosh Was An Item Identified For Additional Analysis • Completed • Simulations in Progress • All Faults Identified Were Able To Say YES to Accepted Risk • Review of All Fault Protection Configuration Files Scheduled For December 4 • Disable FP Entries Into Safe Mode After TCM 13 (E-18 Hours) • Re-Enable FP Post Encounter From The Ground • Verify No Time Bombs • Spacecraft is Safe CERR-ARC

  17. Fault Protection Enables/Disables CERR-ARC

  18. Encounter Test Program • Purpose • Verify S/C Can Survive Safe Mode/Re-Boot In Order To Obtain Primary Science (Dust Collection) • Test Encounter Sequence That Will Obtain Secondary and Tertiary Science (Images, CIDA, DFM, Dynamic) • “Test As You Fly” • 17 Tests Have Been Identified in Test Plan • Nominal 300 Km Flyby • Stacked Errors – 2 Cases • 1000 Km Stacked Error • 3 Sigma Dust • Specified Torques • Fault Protection – 5 Cases • Risk Reduction – 6 Cases • 13 Cases Have Been Completed, Remaining Cases On-Schedule • Additional Cases Will Be Performed As Time Permits CERR-ARC

  19. Encounter Test Program Results • Minor Changes to Encounter Sequence • Identified Y-Axis Controller Improvement • IMU Failed Test • IMU Failed Off • No Attitude Knowledge/Control • Re-Examining Allowing IMU Swap • Test Anomaly Sheets • Documents Test Anomalies, Set-up, etc • Status • 72 Opened • 53 Closed • 46 Related to STL Issues • ENC-1-037 • SM Entry During Nominal Flyby • Experts Have Reviewed All Available Data But Cause Remains Unknown • Has Not Been Duplicated • No Constraint on Testing CERR-ARC

  20. Contingencies • No Waivers To Flight Rules and Constraints • Streamline Existing Safe Mode and LOS Plans for Rapid Recovery • Power Contingency Plan • Requires 4 Solar Array String Failures • Ground Commands to Power Off All Non-Essential Components (Instruments, Catbed Heaters to Non-Op Set –Point) • Telecom Data Rates • In Case Signal Strength Is Lower Than Expected • Commands Exist For Safe Mode Recovery • RCS Thruster Swap • FP Strategy Disable Swap to Secondary RCS Thruster • FP Test Has Verified Current Strategy Will Provide Necessary Attitude Control, TCM Thrusters Keeping S/C Behind Whipple Shield • Ground Will Swap RCS Thruster When Appropriate to Minimize Propellant Usage CERR-ARC

  21. Staffing • ACE Coverage • Prime Shift December 23 – December 30 • 24/7 December 30 – January 3, 2004 • Prime Shift January 4 – January 8, 2004 • SCT Staff Capable Of Supporting 24/7 Operations • Draw on Existing Operations Team (GNS, ODY, MGS), S/S Designers On-Call • Event Related Coverage Prior to January 1 (Primarily Prime Shift) • Everyone On-Call Starting December 23 (After TCM 11) Until January 8, 2004. • 24/7 Coverage January 1 – 2, 2004 • ORT • TCM 12 and Encounter Sequence Performed on Nov 5 • TCM 13 and 14 Scheduled for Dec 9-10 CERR-ARC

  22. READINESS ASSESSMENT • STL Testing Has Sufficient Margin • Spacecraft Is Operationally Ready • Personnel Resources Are Available CERR-ARC

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